1. Grade 9 Geography Mapping Skills – Map Scale
Maps are very useful tools for locating things, determining direction or calculating distances.
What? How do you calculate a real or actual distance from a paper map?

2. Grade 9 Geography Mapping Skills – Map Scale
Calculating real distances…
You need two things from your map AND a mathematical formula to determine real distances:
Map Distance – The measured distance on the map
Scale – A ratio (i.e., each centimetre on the map is how far in real life
Formula – MD/GD = scale where GD is Ground Distance (the real or actual distance)

3. Grade 9 Geography Mapping Skills – Map Scale
Map Distance (MD)
With a ruler, you need to measure the distance ON THE MAP from your starting point to your finishing point.
The example shows a trip starting in Istanbul and finishing near the border with Iran. With a ruler, measure the line. This is the distance on the map or Map Distance (MD)

4. Grade 9 Geography Mapping Skills – Map Scale
Scale is located on the map…usually along a bottom edge
Scale is a statement of the relationship between distances on a map (i.e., Map Distance (MD)) and distances in real life (i.e., Ground Distance (GD)).
As you know, a drawing made according to the scale will be an exact copy of the real object…only smaller.
Scale is always presented as a ratio on a map. For example, scale is given as 1:25,000,000 which means 1 cm on a map is 25,000,000 cm in real life (or 250 km)

5. Grade 9 Geography Mapping Skills – Map Scale
Formula
The formula for calculating the real distance (i.e., Ground Distance (GD)) is a ratio.
If you know Map Distance (MD) and scale, you can “somehow” combine them to calculate GD.
MD / GD = scale

6. Grade 9 Geography Mapping Skills – Map Scale
MD / GD = scale
Example
Scale is 1:37,000,000 or 1 cm = 370 km or 1 / 370
MD = 10.2 cm
What is Ground Distance (GD)?
MD / GD = 1 / 370
Let GD = x
10.2 / x = 1 / 370
x = (10.2)(370) = 3,374
The Ground Distance is 3,374 km

7. Grade 9 Geography Mapping Skills – Map Scale
MD / GD = scale
Try one
Scale is 1:25,000,000 or 1 cm = 250 km or 1 / 250
MD = 13.2 cm
What is Ground Distance (GD)?
MD / GD = 1 / 250
Let GD = x
The Ground Distance is 3,300 km …right?